Learn about this topic in these articles:

demography of Lake Chad region

...from the imposed authority of Kanem’s successor state, Bornu, located southwest of Lake Chad. Some ethnic groups were not assimilated. The metallurgists of Kanem, for example, were apparently the
Danoa (Haddad), who currently serve as blacksmiths among the Kanembu. Other groups resisted integration into the medieval kingdoms. The Yedina (Buduma) established themselves among the inaccessible...